Turbochargers are known which comprise a turbine housing defining a turbine chamber, an exhaust gas inlet to the chamber, an exhaust gas outlet from the chamber, and a passageway which extends between the inlet and outlet and bypasses the turbine chamber. A valve is mounted in the passageway and controlled to selectively open and close the bypass passageway. Such arrangements are provided to enable excess exhaust gas to be delivered to the turbocharger outlet thus controlling the speed of a turbine journaled for rotation in the chamber.
In prior art turbochargers, such as those shown in U.S. Pat. Nos. 3,270,951, 4,120,156, and 4,304,097, the bypass passageway opens into a relatively large side pocket which communicates with the turbine outlet. Thus, when exhaust gas flows through the bypass into the pocket it discharges into the exhaust flow generally at right angles to the direction of gas delivered to the outlet from the turbine chamber. This disturbs the flow of gas through the outlet, thereby increasing back pressure and reducing turbine efficiency. Even when the bypass is blocked by the valve, the efficiency of the arrangement is reduced because the relatively large pocket opening into the turbine outlet disturbs the flow of gas.
It is an object of the present invention to obviate or mitigate the problems outlined above.